Raman and FT-IR spectra of NIPA (N-isopropyl acrylamide) polymer and gel have been studied in the temperature range 20-500C. Spectral changes observed in the C-H and C-C stretch regions during the volume phase transition of the gel show that the polymer and gel undergo structural changes which are very similar to each other.The phase transition involves most probably a conformational change of the isopropyl group.